At Comic-Con International, the geek is king. Once a niche showcase for the latest in science fiction comics, film and TV, the San Diego festival has become the fan's alternative to Cannes; a place where ordinary punters, behind-the-scenes creatives and stars can get together to discuss the cutting edge of popular culture, from fantasy to anime. Last weekend, 130,000 people passed through its doors to see sneak previews of wildly anticipated movies, from The Hobbit to Steven Spielberg's The Adventures of Tintin; they also came to quiz the likes of Andy Serkis and Andrew Garfield at the convention's famed panel discussions, as well as hang out with fellow fanboys and girls – many of them in costume.

The convention centre in which Comic-Con is held, and where it will be staged until at least 2015, is gargantuan. The main action takes place in the 6,500 capacity Hall H and the 4,000 capacity Ballroom 20, which are often rammed to the rafters and impossible to get into at peak times. And, to emphasise the fans-first nature of the enterprise, there is no special guest list for the press: we have to wait in line like everyone else, even if that means sitting for three hours to catch the Game of Thrones panel. After four long days, here's what I learned.

Spielberg's Tintin is Indiana Jones's younger, animated cousin

The exclusive footage Spielberg screened of his animated version of Hergé's story thrilled a capacity audience – especially as he had brought Lord of the Rings producer Peter Jackson along. The motion-capture technology was state of the art, and watching it was almost uncanny – as if inanimate creations had been given a soul. In the main scene we were shown, Tintin encounters Captain Haddock for the first time onboard a storm-lashed ship. Indiana Jones style, the characters are engaged in an intense conversation while the action plays out around them. The movements are supremely naturalistic: almost like watching an enhanced version of the rotoscope technique favoured by Richard Linklater in A Scanner Darkly. Only the motion-captured Na'vi species in Avatar come anywhere close to being as realistic.

Watch out for the Hulk

Less than five minutes after I arrived at Comic-Con, I walked right into an enormous man as he bowled down the main hall. "Do you realise that was Lou Ferrigno?" asked one passerby, admiringly, as I sat dazed on the concourse. As all fans know, Ferrigno was the former Mr Universe champion who became a TV legend when cast as The Incredible Hulk. Comic-Con must be one of the few places on earth where being deposited on your backside by a 6ft 4in actor rushing to a signing session is utterly cool.

Scott's film, due next year, is his first science fiction outing since Blade Runner, 25 years ago. It was originally said to be a prequel to Alien, his 1979 sci-fi slasher; but Scott, over a satellite linkup on location in a remote part of Iceland, said that the films only shared "DNA": "In the last few minutes of the movie you'll understand what we're talking about." Footage was then screened which went some way to explaining the link between the two films. Consisting mainly of rapidly cut shots of the crew of a spaceship, at one point the camera panned up over a wall bearing hieroglyphic-like letters in a style recalling the HR Giger-designed set of the planetoid from the first Alien film; a shot of some mechanical tubes filled with columns of green gunk recalled Alien's "egg room".

Embrace your inner geek

No star gets booed at Comic-Con. Yet those stars who are prepared to prostrate themselves on the fanboy altar will be clasped to the breasts of the faithful and never let go. On Saturday night, before the panel previewing The Amazing Spider-Man, released next summer, a fan dressed in a bad Spidey outfit grabbed the mic at the front of the hall and began emoting, geekily, about how excited he was to be there. Then he whipped off his mask and revealed himself to be Andrew Garfield, who is, you know, actually playing Spider-Man. Was he genuinely overwhelmed by the moment, or taking the mickey out of more than 6,000 fans? Nobody seemed to mind. He understands them.

Aardman have discovered anarchy

Aardman's first movie here is scurvy seadog romp The Pirates! Band of Misfits, also titled The Pirates! In an Adventure with Scientists. The footage director Peter Lord showed suggests that the animation studio's style has evolved. Maybe it was the Clash and Sex Pistols soundtrack, but this seemed altogether more anarchic than Wallace and Gromit: imagine a Monty Python sketch about a motley crew of corsairs, set to stop-motion animation. The voice cast is top-notch: Hugh Grant, Martin Freeman, Brian Blessed, Hugh Laurie and Imelda Staunton (as a pirate-hating Queen Victoria) are joined by Jeremy Piven from HBO show Entourage, Salma Hayek and David Tennant.

The actor's latest motion-captured role, after Gollum in the Lord of the Rings trilogy and King Kong, is an intelligent chimpanzee in science fiction reboot Rise of the Planet of the Apes. He told the audience: "Whenever I choose a role people say 'Why are you playing another monkey?'

"I'll just chart the development of this character for you. He's a young, innocent soul who is brought into this world. He's brought up by human beings, nurtured, loved and cared for. He's then taken away from his family and thrown into a hardcore prison for apes. He brings this disparate group of apes together and leads them to revolution. It's an amazing journey." So now you know.

Don't disrespect the fans

Rhys Ifans got arrested after a scuffle with a security guard on Saturday night, despite co-starring in arguably the biggest film to appear here, The Amazing Spider-Man. Steven Spielberg and Peter Jackson went out of their way to prove to the crowd that they were "just two Tintin fanboys" during the panel for the adventure. At Comic-Con, the geek rules, and anyone else needs to watch themselves a bit.

A nice one-liner never goes amiss

Some of the most prosaic questions from fans provoked the best responses from stars. "Were you confused during the filming of Memento?" Guy Pearce was politely asked during a Q&A session. "I don't remember," responded the Australian actor, to cheers (the film is about an amnesiac). Better still was the reaction when a fan asked the entire Game of Thrones panel to reveal how they thought the HBO fantasy series should end. After a series of banal replies, it was actor Peter Dinklage's turn to duck his head towards the mic. "Dance number," he deadpanned.

Smith's Saturday night "state of the geek nation" address made the case for his talent much more effectively than his most recent movies. Smith is giving up making films in order to run internet radio station smodcast.com. "Movies are not my first language – talking is," he said. "Visually speaking, I'm not that adept and I'm ready to put that medium aside. I'm going to make one more movie, and after I'm done with that I'll step aside and make room for the younger guy."

While he may be at a low point in his film career, Smith is currently at the peak of his powers as an orator. He was on stage for more than two hours, was consistently hilarious (a series of gags about the Westboro Baptist church were particularly on-button), and had the audience eating out of his hands.

Crude jokes can go dangerously awry

Patrick Stewart was the highlight of an (admittedly tedious) panel for animated musical Dorothy of Oz on Saturday afternoon, gamely answering questions and making polite noises about the film's creative team, until some idiot decided to ask him for "bum sex" in front of 6,000 baying Star Trek fans. He was not happy. Panellists also need to be wary: Smith was bluer than the Pacific during his Saturday night stint, yet repeated attempts by Twilight's Kellan Lutz to raise a lewd chuckle by referring to himself as the "God of wetness" during the Immortals panel (he's playing Poseidon), only resulted in tumbleweed blowing painfully through the hall.

Correction 27/7/11: In the editing process, we gave the mistaken impression that a clip of The Hobbit was shown at Comic-Con. This wasn't the case, though there was a panel on the subject.